Modulation and equalization in an orthonormal time-frequency shifting communications system

Abstract

A method of receiving data including receiving, on one or more carrier waveforms, signals representing a plurality of data elements of an original data frame wherein each of the data elements are represented by cyclically time shifted and cyclically frequency shifted versions of a known set of waveforms. The method further includes generating, based upon the signals, a received data frame and generating an equalized data frame by performing an equalization operation using elements of the received data frame, the equalization operation correcting for distortion introduced into the signals during propagation of the carrier waveforms through a channel.

What is claimed is: 
     
       1. A method, comprising:
 receiving, at a signal receiver, a received orthonormal time-frequency shifting (OTFS) signal wherein the received OTFS signal includes a plurality of echo reflections of a transmitted OTFS signal comprised of cyclically time shifted and cyclically frequency shifted waveforms, each of the plurality of echo reflections comprising at least one of a time-shifted signal component and a frequency-shifted signal component; 
 evaluating the cyclically time shifted and cyclically frequency shifted waveforms in order to detect the at least one of the time-shifted signal component and the frequency-shifted signal component of ones of the plurality of echo reflections; and 
 generating, based upon the evaluating, corrective information useful in correcting for effects of the plurality of echo reflections. 
 
     
     
       2. The method of  claim 1  further including sending the corrective information to a transmitter from which the transmitted OTFS signal was previously transmitted. 
     
     
       3. The method of  claim 1  further using the corrective information to equalize the OTFS signal by shifting ones of the plurality of echo reflections relative to a primary received signal component. 
     
     
       4. The method of  claim 1  wherein the evaluating includes using pattern matching to evaluate patterns associated with the cyclically time shifted and cyclically frequency shifted waveforms. 
     
     
       5. The method of  claim 1  wherein the transmitted OTFS signal is generated by transforming a data frame including a plurality of data elements into a transformed data matrix having a plurality of transformed data elements wherein ones of the plurality of transformed data elements are based upon multiple ones of the plurality of data elements and wherein the data frame has a first dimension of at least N data elements and a second dimension of at least N data elements, wherein N is greater than one. 
     
     
       6. The method of  claim 1  wherein the transmitted OTFS signal is generated by transforming a data frame including a plurality of data elements into a two-dimensionally spread data matrix and tiling each column of the two-dimensionally spread data matrix as a function of one of time and frequency. 
     
     
       7. A receiver, comprising:
 a processor; 
 a memory including program code executable by the processor, the program code including: 
 code for receiving, at a signal receiver, a received orthonormal time-frequency shifting (OTFS) signal wherein the received OTFS signal includes a plurality of echo reflections of a transmitted OTFS signal comprised of cyclically time shifted and cyclically frequency shifted waveforms, each of the plurality of echo reflections comprising at least one of a time-shifted signal component and a frequency-shifted signal component; 
 code for evaluating the cyclically time shifted and cyclically frequency shifted waveforms in order to detecting the at least one of the time-shifted signal component and the frequency-shifted signal component of ones of the plurality of echo reflections; and 
 code for generating, based upon the evaluating, corrective information useful in correcting for effects of the plurality of echo reflections. 
 
     
     
       8. The receiver of  claim 7  wherein the program code further includes code for facilitating sending of the corrective information to a transmitter from which the transmitted OTFS signal was previously transmitted. 
     
     
       9. The receiver of  claim 7  wherein the program code further includes code for using the corrective information to equalize the OTFS signal by shifting ones of the plurality of echo reflections relative to a primary received signal component. 
     
     
       10. A non-transitory computer readable medium including program instructions for execution by a processor in a signal receiver, the program instructions comprising instructions for causing the processor to:
 receive, at a signal receiver, a received orthonormal time-frequency shifting (OTFS) signal wherein the received OTFS signal includes a primary signal component and at least one echo reflection of a transmitted OTFS signal comprised of cyclically time shifted and cyclically frequency shifted waveforms, the echo reflection comprising at least one of a time-shifted signal component and a frequency-shifted signal component; 
 evaluate the cyclically time shifted and cyclically frequency shifted waveforms in order to detect at least one of an extent of a time shift of the time-shifted signal component relative to the primary signal component and an extent of a frequency shift of the frequency-shifted signal component relative to the primary signal component; and 
 generate, based upon the at least one of the extent of the time shift and the extent of the frequency shift, corrective information useful in correcting for effects of the at least one echo reflection. 
 
     
     
       11. The non-transitory computer readable medium of  claim 10  wherein the program instructions further include instructions for facilitating sending the corrective information to a transmitter from which the OTFS signal was previously transmitted. 
     
     
       12. The non-transitory computer readable medium of  claim 10  wherein the program instructions further include instructions for using the corrective information to equalize the OTFS signal by shifting the time-shifted signal component and the frequency-shifted signal component relative to a primary received signal component. 
     
     
       13. A method, comprising:
 receiving, at a signal receiver, a composite signal including a plurality of echo reflections of a transmitted signal wherein the transmitted signal is comprised of cyclically time-shifted and cyclically frequency-shifted waveforms; 
 evaluating the cyclically time shifted and cyclically frequency shifted waveforms of the plurality of echo reflections in order to detect at least one of a time-shifted signal component and a frequency-shifted signal component of ones of the plurality of echo reflections; and 
 generating, based upon the evaluating, corrective information useful in correcting for effects of the plurality of echo reflections. 
 
     
     
       14. The method of  claim 13  further including sending the corrective information to a transmitter from which the composite signal was previously transmitted. 
     
     
       15. The method of  claim 13  further using the corrective information to equalize the composite signal. 
     
     
       16. A method of receiving data, comprising:
 receiving, on one or more carrier waveforms having propagated through a communication media, a primary signal and echo reflection signals representing a plurality of data elements of an original data frame wherein each of the data elements are represented by cyclically time shifted and cyclically frequency shifted versions of a known set of waveforms; 
 generating, based upon the primary signal and the echo reflection signals, a received data frame; 
 evaluating ones of the cyclically time shifted and cyclically frequency shifted versions of the known set of waveforms to determine time and frequency equalization parameters useful in correcting for effects of the echo reflection signals; and 
 generating an equalized data frame by performing an equalization operation using elements of the received data frame, the equalization operation correcting for distortion introduced by at least the echo reflection signals. 
 
     
     
       17. The method of  claim 16  wherein the received data frame is of dimension N×N, where N is greater than one.